Spain wins in London: the Court of Appeal confirms that an ICSID award cannot be assigned without the State's consent

The Court of Appeal of England and Wales has handed Spain a victory with systemic potential on the renewables arbitrations front. In the judgment of 2 November 2026, Blasket Renewable Investments LLC v the Kingdom of Spain ([2026] EWCA Civ 1392), the court - with Lord Justice Foxton giving the leading judgment and Lords Justices Lewison and Males concurring - confirms that an award rendered under the ICSID Convention cannot be assigned by the creditor investor without the consent of the debtor State, and that, without that consent, the assignee cannot seek its recognition or enforcement in England and Wales.

The litigation is part of the wave of arbitrations against Spain under the Energy Charter Treaty and the ICSID Convention arising from the reforms of the renewables remuneration regime applied between 2010 and 2014. In 2019, Maltese and Swiss investors obtained an award of 29.3 million euros against Spain, registered in 2021 in the High Court under section 1(2) of the Arbitration (International Investment Disputes) Act 1966. In 2024, the investors assigned their rights under the award to Blasket, a litigation funding fund based in Delaware, which applied to be substituted for the investors in the English enforcement proceedings. Judge Pelling KC, of the Commercial Court, refused the substitution and the fund appealed.

Four findings that close the route

The unanimous judgment articulates four main findings. First, customary international law does not permit the assignment of treaty-based rights without the consent of the obliged State, and that rule applies equally to private holders of international law rights derived from the ICSID Convention and from an award that exists solely on the international plane. The court rejects the argument, inspired by the Lotus principle, that the absence of a specific prohibition of assignment in international law would imply its lawfulness.

Second, correctly interpreted, article 54.2 of the ICSID Convention only allows one of the original parties to the award to request its recognition or enforcement, not an assignee. Third, the Convention does not refer the question of the assignability of awards to the domestic law of the contracting States. And fourth, the registration of the award in the High Court pursuant to section 2(1) of the 1966 Act does not create new substantive English law rights capable of assignment even where the award itself is not assignable.

The architecture of the ICSID Convention, at the centre

The core of the debate is the legal nature of the ICSID award. Unlike a commercial award, which circulates through the domestic law of each State, an award rendered under the ICSID Convention lives exclusively on the plane of international law: its effects, its binding force and the routes to seek its recognition and enforcement are exhausted in what the Convention itself provides. Hence the second finding of the judgment: if article 54.2 only empowers the original parties to request recognition or enforcement, an assignee - which was not a party to the arbitration - lacks title to appear before the English courts. And hence also the third: that conclusion cannot be supplemented by resorting to domestic law, because the Convention contains no reference to national laws to decide whether the award is or is not transferable.

The fourth argument answers a concrete strategy of the assignees: maintaining that the registration of the award in the High Court pursuant to the Arbitration (International Investment Disputes) Act 1966 "Anglicises" the credit and turns it into an assignable asset like any other. The Court of Appeal rejects it: registration is an enforcement mechanism provided by the 1966 Act to comply with the obligations of the Convention, not a source of new substantive English law rights. What is not assignable on the international plane does not become assignable by the mere fact of its registration for enforcement.

Against the case law of the United States and Australia

The Court of Appeal expressly accepts that its conclusion diverges from first-instance decisions of the United States and Australia and from a Dutch interlocutory decision. Lord Justice Males went so far as to express the hope that the judgment would contribute to an eventual international consensus, observing that this "should not be an area in which the concept of first seised carries undue weight". The court left open the question of involuntary transmissions, such as those arising from the death or insolvency of the award creditor. Blasket, according to the note from Spain's counsel, has sought permission to appeal to the UK Supreme Court.

Why the judgment transcends this case

The business that is shaken is that of buying and selling awards against States. Specialised funds acquire collection rights from investment awards - often at a discount - to enforce them in jurisdictions holding State assets. If the ICSID award is not assignable without the consent of the debtor State, that secondary market loses its foundation in the key jurisdiction of London, a habitual centre of enforcement due to the presence of assets and the pro-enforcement tradition of its courts. For Spain, with dozens of renewable awards and proceedings underway and a procedural position that systematically fights the enforcement of ICSID awards in domestic courts, the doctrine is a first-order defensive asset. Spain was represented by Simmons & Simmons LLP, with Sean Aughey of Essex Court Chambers alongside Cameron Miles and Raphaël Tulkens of 3VB.

The judgment also lands at a delicate moment for the secondary market in arbitration claims. The funds that acquired stakes in renewable-energy awards against Spain did so assuming that assignment was an ordinary transaction; from now on, the debtor State's consent clause becomes an unavoidable due diligence point in any such deal, and the choice of enforcement forum becomes a strategic decision as relevant as the acquisition itself. For Spain, the judgment offers an argument that can be replicated in other jurisdictions where enforcement of awards by assignees is pursued.

The question is not closed: it depends on the Supreme Court's permission to appeal and on how other jurisdictions react. But those working in investment arbitration have, as of this week, a Court of Appeal precedent - a body whose doctrine weighs throughout the common law - that changes the risk analysis of any award assignment.

You can also read our coverage of the CJEU doctrine on State aid to airlines and of the October insolvency proceedings, as well as the analysis of mortgage enforcement in insolvency without an estate under STS 1649/2026.

Sources

• Courts and Tribunals Judiciary: OperaFund Eco-Invest Sicav Plc and others v the Kingdom of Spain, [2026] EWCA Civ 1392
• Essex Court Chambers: "Court of Appeal Unanimously Holds That ICSID Awards Cannot Be Assigned Without the Debtor State's Consent"
• El Confidencial: "A UK judgment blows up the business of selling renewable awards against Spain"